Conventional specific gravity measuring apparatuses include one which is described in Japanese examined utility model registration publication No. H04-49571. This specific gravity measuring apparatus is composed of a liquid bath filled with a liquid, a measured object receiving member which is housed in the liquid bath via a support means in a non-contact manner and into and out of which the liquid within the liquid bath can freely flow, an aerial mounting member which is supported by the support means and on which a measured object is placed in order to measure gravity thereof in the air, and a weighing apparatus which receives and supports the measured object receiving member via the support means, wherein the weighing apparatus is provided with a sensor which converts a weight acted upon the measured object receiving member into an electrical signal and a measuring section which measures specific gravity of the measured object from an output of the sensor at the time when the measured object is placed on the aerial mounting member and an output of the sensor at the time when the measured object is submerged and placed on the measured object receiving member, and the aerial mounting member comprises a lid body attached to the support means so as to fully open and close an opening at an upper part of the liquid bath. To use this specific gravity measuring apparatus, the aerial mounting member comprising the lid body is attached to close the opening at the upper part of the liquid bath. In this state, the measured object is placed on the aerial mounting member, and a weight in air of the object is measured. After that, the aerial mounting member is detached from the support means to open the upper opening of the liquid bath. In this state, the measured object is sunk into water and placed on the measured object receiving member. Then, the aerial mounting member is closed again, and in this state, a weight in water of the measured object is measured. The specific gravity of the measured object is measured by a difference between the weight in air and the weight in water of the measured object having been measured in the afore-described manner.